All API calls take a service_id parameter. This parameter can be used to call a single survice,
or it can be used to enable various "fetching modes".

fallback to denote you want to use the first working service. Each currency
has an ordered list of defined services. Using this mode guarantees a result
(from somewhere) will always be returned.
This service can be thought as being "high availability".

paranoidN to enable paranoid mode. This will call N services, and verify that they all
return the same data. If any service returns a different value, the call will indicate this.
In the case of a paranoid mode failure, the underlying cryptocurrency network may be forked.

averageN can be used to calculate the average of N service calls.
This mode is helpful for determining the optimal transaction fee and current price.
This mode does not apply to many blockchain operations since all services return the exact same data.

privateN can be used to on services that take multiple addresses.
One service will be used for each addresses passed in. This mode is applicable to
`address_balance`, `unpent_outputs` and `historical_transactions`. All calls will be
spread out over N number of seconds. The higher value of N passed
throug, the higher level of privacy achieved. Max value for N is 30.

Current Price

URL general form:https://multiexplorer.com/api/current_price/[service_id]?[fiat=fiat|currency=currency]

service_id is a number corresponding to the service number in the table above,
or a servcie mode such as "fallback", "average3". Note, "paranoid mode"
and "private mode" does not apply in the context of current price.

The currency argument is required. Enter three leter cryptocurrency code.

The fiat argument is required. Enter three leter fiat currency code.

The include_raw argument is also optional. Setting it to true will include
the raw_response field in the response.

Address Balance

service_id is a number corresponding to the service number in the table above,
or a servcie mode such as "fallback", "paranoid3". Note, "average mode" does not
apply in the context of address balance. If private mode is used, multiple addresses
must be passed in via the `addresses` argument, (comma seperated).

The currency argument is optional. If you leave it off,
the currency will be guessed from decoding the address version byte.

The include_raw argument is also optional. Setting it to true will include
the raw_response field in the response.

Recommended Transaction Fee

URL general form:https://multiexplorer.com/api/optimal_fee/[service_id]?currency=[curency_code]

service_id is a number corresponding to the number in the table above,
or a service mode such as "fallback", "paranoid3". Note, only "average mode" applies for the optimal fee endpoint.
Each service returns a different value, so it makes sense to use the value of each service averaged together.
Paranoid mode will always fail, because rarely do each service return the exact same recommended fee.

The currency argument is required. Must be 3 or 4 letter code.

The include_raw argument is also optional. Setting it to true will include
the response as it was returned directly from the service.

Returned is the amount of satoshi's that should be added as a transaction fee per KiB (1024 bytes).